Automatic test equipment (ATE) plays a role in the manufacture of semiconductor devices and circuit board assemblies. Manufacturers generally use automatic test equipment, or “testers,” to verify the operation of devices during the manufacturing process. Such devices are referred to as a “device under test” (DUT) or a “unit under test” (UUT). Early detection of faults eliminates costs that would otherwise be incurred by processing defective devices, and thus reduces the overall cost of manufacturing. Manufacturers also use ATE to grade various specifications. Devices can be tested and binned according to different levels of performance in areas, such as speed. Devices can be labeled and sold according to their actual levels of performance.
In recent years, many types of legacy ATEs have been replaced with newer, higher-performance ATEs. Although such newer testers have many new features, many of the test programs that run on these newer testers have already been written, and depend on the performance characteristics of legacy ATEs. However, a newer ATE may not necessarily have the same performance characteristics as the legacy ATE. This can affect how existing programs are used with newer, or successor, ATE. For example, in older test instruments, memory was scarce. Older bus standards also made filling and retrieving memory time-consuming. So, while some test engineers would inadvertently overrun available memory, others would intentionally use undocumented features to loop around, overwrite, or otherwise re-use memory locations.